Electric discharge tube



J. G. W. MULDER ELECTRIC DISCHARGE TUBE Filed Dec. 11, 1928 Fatented Oct. 18,- 1932.

UNETED- si'rA-rss "PATENT ornce JOEANNES GIJSBERTUS WILHELM MULDER, OF EINDHOVEN, NETHERLANDS, AS-

SIGNOE TO N. V. PHILIPS GLOEILAMPEN-FABRIEKEN, 0F EINDHOVEN,-NETHEB- LANDS, A LIMITED LIABILITY COMPANY ,OF THE NETHERLANDS nnnc'rnic nrscnnncn TUBE Application filed December 11, 1928, Serial No. 325,229, and in the Netherlands February 11, 1928.

This invention relates to'an electric discharge tube, more particularly to a discharge tube adapted to rectify polyphase alternating currents and comprising an incandescent cathode and at least three anodes.

In the hitherto known polyphase rectifiers comprising an incandescent cathode and at least three anodes, the incandescent cathode and the anodes are each mounted on a separate stem. This construction introduces difiiculties in the manufacture of rectifying valves which are usually of glass, as such tubes on account of their particular shape can only be blown by skillful artisans and are not adapted for mechanical manufacture.

Now, a construction has been'found which permits of polyphase rectifier valves having at least three anodes being manufacturedas far as possible mechanically and consequently of being made on a large scale.

An electric discharge tube according to the invention which is adapted to rectify polyphase alternating currents comprises an 1n-.

candescent cathode and at least three anodes said electrodes being mounted on two stems.

The incandescent cathode and one anode may be mounted on a single stem and the remaining anodes on the other stem or the incandescent cathode and two anodes may be arranged on a single stem and the remaining anode or anodes on the other stem. In a dif ferent but also useful construction the incandescent cathode is mounted on one stem and the anodes on the other stem.

The rectifier may be provided inside with means operative to increase the back ignition voltage and these means may be constituted by cylindrical hoods preferably provided with constrictions. These hoods may be adapted to conduct electricity and insulated from the anodes to which they are connected with the interposition of a condenser that.

may be variable.

The invention wlll be more clearly under-- 5 stood by reference to the accompanying draw- Referring to Figure 1, the wall of the rectifier valve, which may be for example of glass, is designated by -1.- This valve has sealed to it a stem 2. having a pinch 8 and also a stem 4 having a pinch 5. Theleads 6 of. the

incandescent cathode 7 are secured to the candescent cathodes for example tungsten- I thorium-, or molybdenum-thorium cathodes may likewise be used but oxide cathodes are to be preferred since they are more efficient.

By providing for wide windings of the cathode it is ensured that not only that part of the cathode surface that is turned to the outside emits electrons but that this surface takes part in the emission throughout the circumference of the wire. I

The pinch 3 has also mounted on it an anode 8 surrounded by a hoodof insulating material 9 which has a constriction 10. The lead 11 of the anode 8 is surrounded by an insulating cylinder 12.

The stem 4 has mounted on it two other anodes 8 which are also surrounded by hoods The rectifier shown in Fig. 2 has a stem 2 on which is mounted an incandesciblecathode .7 and two anodes 8, a third anode 8 being disposed on a second stem 4., Each anode is surrounded by a hood 9 having constricted portions 10, and being formed'of conductive material. The electrically conducting hoods 9 are connected by wires 13, with the interposition of condensers 14 that may be variable, to the leading-in wires 15 of the anodes 8.

For the rest the remaining parts in this figure are designated by like reference numerals as the identical parts of Figure 1.

What I'claim is:

1. An electric discharge tube comprising only two stems, an incandescible cathode and at least three anodes, all said electrodes being mounted on said two stems, and screens between the anodes, each of said screens consist-ing of a cylindrical metal hood surrounding each of the anodes.

2. An electric discharge tube, comprising .i an envelope, two opposed stems in said en- I velope, at least two anodes mounted on one.

1o stem, and at least one anode mounted on the other stem and facing said first-mentioned anodes, an incandescible cathode mounted on one of said stems, and a conductive hood surrounding and projecting 15 slightly beyond each of said anodes. V

3. A gas filled electric discharge tube, comprising an envelope, two opposed stems in said envelope, at least two anodes mounted on one stem, and at least one anode mount- 1 ed on the other stem and facing said firstmentioned anodes, an incandescible cathode mounted on one of said stems, and a conductive hood surrounding and projecting slightly beyond each of said anodes, the said :45 hoods being constricted just in front of the outer most extremities of said anodes, the hoods then extending outwardly with transverse dimensions slightly larger than the remainder thereof. i

3o 4. An electric discharge tube, comprising an envelope, two opposed stems in said envelope, at least two anodes mounted on one stem, and at least one anode mounted on the other stem and facin said first-mentioned rm anodes, an incandesci ble cathode mounted on said second-mentioned stem, with the single. anode, and extending transversely across the space between the anodes of the said two stems, and a conductive hood surrounding 40 and projecting slightly beyond each of said anodes, to prevent discharge directly therebetween. V

5. An electric discharge tube comprising an envelope, two opposed stems in said en- 45 velope, at least two anodes mounted on one stem, and at least one anode mounted on the other stem and facing said first-mentioned anodes, an incandescible cathode mounted on said first-mentioned stem in a plane between the two anodes thereon. and extending transversely across the space between the anodes of the said two stems, and a conductive hood surrounding and projecting slightly beyond each of said anodes, to prevent discharge directly therebetween.

In testimony whereof I have signed my name to this specification.

JOl-IANNES GUSBERTUS WILHELM MULDER. 

